Automatic chain identification method and apparatus

ABSTRACT

Chain printers presently in the art are constructed to permit replacement or changing of the type carriers to facilitate the use of a variety of character sets or fonts. In order to handle a plurality of type slug carriers of different fonts, a translator must be provided for each font set. In order to indicate that the translator being used matches the font set of the type carrier placed on the printer, several teeth on the type carrier are filed down. The filed teeth are later sensed as an identification code unique to that type carrier. This code is stored in a register in the printer controller to be compared with a code in another register that identifies the translator being used.

United States Patent H Bovett et al.

[45] Apr. 29, 1975 AUTOMATIC CHAIN IDENTIFICATION METHOD AND APPARATUS[73] Assignee: Burroughs Corporation. Detroit.

Mich.

22 Filed: Dec.26. I973 21 Appl. No.: 427.417

OTHER PUBLICATIONS IBM Technical Disclosure Bulletin. Vol. IS. No. to,

March I973. Gilbreth et al.. pp. 3113-3] [4.

Primary Examiner-Edgar S. Burr Asxistum blruminer-Edward M. CovenAttorney. Agent. or F irmAlhin H. Gess; Nathan Cass: Kevin R. Peterson[57] ABSTRACT Chain printers presently in the art are constructed topermit replacement or changing of the type carriers to facilitate theuse of a variety of character sets or fonts. In order to handle aplurality of type slug carriers of different fonts. a translator must beprovided for each font set. In order to indicate that the translatorbeing used matches the font set of the type carrier placed on theprinter. several teeth on the type carrier are filed down. The filedteeth are later sensed as an identification code unique to that typecarrier. This code is stored in a register in the printer controller tobe compared with a code in another register that identifies thetranslator being used.

10 Claims. 3 Drawing Figures MENTEB Z E S 3. 880, 075

sum 1 OF 2 BCDEFGH WWI/72? $1 jay w 2 17 WNW era/m2 m/rwr 0 0 0 0AUTOMATIC CHAIN IDENTIFICATION METHOD AND APPARATUS BACKGROUND OF THEINVENTION The present invention relates generally to improvements inchain printers and more particularly pertains to the type of chainprinters that are able to interchangeably utilize a variety of differentfont set type carriers. Examples of such printers can be found inpatents having U.S. Pat. Nos. 3.699.884 and 3.629.861.

When a variety of interchangeable font set type carriers are availablefor use on the same printer. a broblem arises in insuring that thetranslate table. utilized for converting the character code signals intotype carrier position signals. matches the particular font set typecarrier that has been placed in the printer.

SUMMARY OF THE INVENTION An object of this invention is to prevent achain printer from operating with a type carrier having a character orfont set that does not correspond with the translator being used.

Another object of this invention is to compare the identification codegenerated by the type carrier placed in the chain printer with the codeidentifying the trans- BRIEF DESCRIPTION OF THE DRAWINGS Other objectsand many of the attendant advantages of this invention will be readilyappreciated as the same becomes better understood by reference to thefollowing detailed description when considered inconjunction with theaccompanying drawings in which like reference numerals designate likeparts throughout the figures thereof and wherein:

FIG. 1 shows a perspective view of drive wheels and a type carrier thatis common to a chain printer.

FIG. 2 illustrates in block and logic diagram form an embodiment of thecircuitry associated with the present invention.

FIG. 3 is a pulse diagram illustrating the signals present at variouspoints of the circuitry .of FIG. 2 during its operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates the typicalarrangement in a chain printer of a type carrier l5-and driving wheelsIl.and 13. The type carrier. or belt 15, has mounted thereon a pluralityof type slugs which carry the font set 17 illustrated as the blockedalphabet A, B, C, D etc. The type slugs are backed with teeth 19 thatengage the driving wheels I] and 13 to be driven in a non-slippingmanner.

The font set of a particular type carrier may be identified by filingflat a certain minimal combination of these teeth 19. For example, byfiling down three teeth 21. 23 and 25. a certain six-bit identificationcode may be produced. This provides for 2" unique identification codes.The first flattened tooth 2!. assuming the type carrier is moving in acounter-clockwise direction. represents a synchronizing pulse. The sixteeth that follow that synchronizing pulse represent the six digit typecarrier identification code. This code is generated by a reluctance-typesensing device 27 every time that a flattened tooth. like 23 forexample. passes the reluctance sensor 27. Reluctance sensors areconsidered well known in the art and will not be further discussedherein. Every time a flattened tooth passes the sensor. a pulse isgenerated on line 29 which delivers that pulse to the printer control31. The printer control interfaces with a computer system over acommunication link 33. Any well known printer control utilized for chainprinters may be utilized for printer control 3!. For example. the US.Pat. Nos. 3.699.884 and 3.629.861 illustrate one type of printer controlthat may be used.

FIG. 2 illustrates an example of structure to practice the presentinvention. This logic circuitry 35 is made up ofa pair of AND gates 37..39; a D-type flip-flop 41 that receives the output of AND gate 39; aone-shot multivibrator 43 that receives the output of the flip-flop 41;a clock source triggered by the multivibrator 43 for clocking data fromAND gate 37 into a serial-input parallel-output register 47 and aparallel input. paralleloutput register 49; and a comparator 51 forreceiving the outputs of the two registers 47 and 49 and generating asignal to indicate a match. or mismatch.

The operation of the circuitry of FIG. 2 will now be explained inconnection with the pulse trains of FIG. 3. The parallel-input.parallel-output register 49 which. for example. may be a buffer registermanufactured by the Signetics Corporation. and listed in their I972catalogue on page 3-16 as Buffer Register No. 8202. receives the binarycode identifying the translate table being used. This buffer registermay be loaded with. for example. a six-bit binary code from the computersystem. which contains the translate table in memory. over acommunication link 33, or it may be manually inserted. either methodbeing well known in the art and not comprising any part of thisinvention. Prior to the initiation of a print cycle, and during theinitializing stage. then. the buffer register 49 is loaded with aparticular binary code. For purposes of example. it shall be assumedthat the binary code loaded into the buffer register 49 is OIOOIO, asshown in FIG. 3.

Upon a particular type carrier 15 (FIG. I being placed on the chainprinter. prior to a print cycle. the type carrier is rotated severalfull revolutions so that the reluctance pickup 27 can sense theflattened teeth on the carrier. The reluctance pickup 27 senses theflattened teeth and generates a pulse on line 29 which is connected tothe appropriate circuitry in the printer control. The appropriatecircuitry 35 in the printer control receives these pulses at point Awhich are illustrated in FIG. 3 as pulses 73, and 77. These are thepulses generated for the specific example of flattened teeth in F 1G. 1.Obviously. many other combinations of flat teeth might be used. Theexample chosen represents a six-bit identifying code.

Prior to the reception of any pulses by the logic circuit 35 in theprinter control 31, the signal output of the one-shot multivibrator 43in the logic circuit 35, which is illustrated at B of FIG. 3, is low.causing an enabling input to supplied to AND gate 39. This same signallevel is also supplied to AND gate 37 as an inhibiting signal. At thetime of occurrence. of the first pulse 73 sensed by the pickup 27. ANDgate 39 generates a pulse output on line 67 that is supplied to theclock input of D-typc flip-flop 4l causing the 0 output of the flip-flopto send a signal on line 69 to the one-shot multivibrator 43, therebyinitiating it. It may be assumed. for purposes of example. that themultivibrator is of the type manufactured by the Signetics Corporationand described in their 1972 parts catalogue on page Z-l l2 as MonostablcMultivibrator No. N74l2l.

Upon being initiated. the output of the multivibrator 43 goes highthereby inhibiting AND gate 39 and enabling AND gate 37. in addition.this high signal level is supplied over line (ii to a clock source 45causing the clock source to provide clocking signals. over line 63. to amodulo counter 46 and a register 47 and. over line 65. to anotherregister 49.

The clock source 45 may be the printer control system clock which istapped by the signal on line 6i or a timer. such as produced by theSignetics Corporation and described in their I972 catalogue on page 6-4)as Timer No. 555. that is synchronized to the printer control clock.

These clock signals. illustrated at D in FIG. 3. cause the data pulses.appearing at the output of AND gate 37. on line 71 to be clocked intothe type carrier identification register 47. Register 47 may be of thetype manufactured by the Signetics Corporation and described in their1972 catalogue on page 3-78 Serial input. Parallel-output Shift RegisterNo. 78273. Thus for example of flattened teeth illustrated in FIG. 1.the pulses 75 and 77, as well as the lack of pulses therebetween.occuring after the initial synchronizing pulse 73.

within the window generated by the multivibrator 43 causes the contentsof register 47 to be 010010. Any pulses appearing on line 71 after thetime-out of the one-shot multivibrator 43 at 8| will not be clocked intothe type carrier identification register 47.

Upon the last bit of the six bit code being clocked into the register47. the modulo counter 46, which may. for example. be a divide by sixmodulo counter such as manufactured by the Signetics Corporation anddescribed in their 1971 TTL family catalogue on page lOl as Divide bySix Counter No. S5492. would. upon the occurrence of the sixth clockpulse 83 on line 63 cause a pulse to be generated and supplied to acomparator 51 by way of line 64.

At this time the six-bit binary code identifying the type carrier iscompletely loaded in the type carrier identification register 47. Bufferregister 49. and type carrier identification register 47 have theircontents clocked out to comparator Si by the last clock pulse 83.

The comparator 51 may be a pre-packaged computer circuit manufactured bythe Fairchild Corporation and listed in their June 1972 catalogue onpage 8-l24 as Comparator No. 9324. The output of the modulo counter 47on line 64 would be connected to the enable input of the comparator.Only the output of the comparator would be utilized. Thus, in case of amismatch between any of the like bits being compared. out of thecontents of registers 47 and 49, it would be indicated as a signed levelon line 53 of the comparator 51.

This signal may be supplied to the computer system (not shown) toinhibit the print cycle or may simply be supplied to a display device(not shown) to warn an operator that a type carrier having an incorrectfont set has been loaded onto the chain printer.

What has been described is a method and particular apparatus forpreventing a type carrier to be utilized in a chain printer whenever itsparticular translate table is not loaded in the computer system.Obviously many modifications and variations of the invention arepossible in light of the above teachings. It is therefor to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

l. in a chain printer wherein the type carrier has a font set thereonand utilizes a plurality of teeth for engaging driving mens. apparatusfor generating a unique binary code identifying the font set on thecarrier comprising:

a predetermined plurality of flattened teeth located on said typecarrier so as to be representative of said unique binary code;

sensing means adjacent said type carrier for sensing the flattened teethwhen said type carrier is being driven; and

means responsive to said sensing means for generating a binary coderepresentative of the sensed flattened teeth.

2. The apparatus of claim I further comprising:

means for storing the binary code representative of the sensed flattenedteeth;

means for storing a standard binary code; and

means for comparing the binary codes stored in said storing means.

3. The apparatus of claim 2 wherein said storing means for storing abinary code representative of the sensed flattened teeth comprise aserial-input. paralleloutput shift register.

4. In a chain printer wherein the type carrier has a font set thereonand utilizes a plurality of teeth for engaging driving means. a methodfor generating a unique binary code identifying the font set on the typecarrier comprising:

flattening a plurality of teeth on said carrier in a preselected orderrepresentative of said unique binary code;

sensing the flattened teeth when said type carrier is driven; and

generating a binary code representative of the sensed flattened teeth.

5. The method of claim 4 further comprising:

storing the binary code representative of the sensed flattened teeth;

storing a standard binary code; and

comparing the stored binary codes.

6. In a chain printer wherein the type carrier has a font set thereonand utilizes a plurality of teeth for engaging driving means, one ofsaid teeth being physically modified and sensed by a detection means forgenerating a synchronizing pulse, apparatus for generating a uniquebinary code identifying the font set on the carrier. comprising:

an additional plurality of physically modified teeth located on saidtype carrier displaced from the physically modified tooth forrepresenting said binary code. said additional plurality of physicallymodified teeth being sensed by said detection means; and

means responsive to said detection means for generating the binary coderepresented by said representing means.

7. The apparatus of claim 6 further comprising:

means for storing the generated binary code:

means for storing a standard binary code: and

means for comparing the binary code stored in said storing means.

8. The apparatus of claim 7 wherein said physically modified teeth areflattened. and wherein said storing means for storing the binary codegenerated by said detection responsive means comprises a seriaLinput.parallel-output shift register.

9. In a chain printer wherein the type carrier has a font set thereonand utilizes a plurality of teeth for engaging dri ing means. a methodfor generating a unique binary code identifying the font set on the typecarrier.

1. In a chain printer wherein the type carrier has a font set thereonand utilizes a plurality of teeth for engaging driving mens, apparatusfor generating a unique binary code identifying the font set on thecarrier comprising: a predetermined plurality of flattened teeth locatedon said type carrier so as to be representative of said unique binarycode; sensing means adjacent said type carrier for sensing the flattenedteeth when said type carrier is being driven; and means responsive tosaid sensing means for generating a binary code representative of thesensed flattened teeth.
 2. The apparatus of claim 1 further comprising:means for storing the binary code representative of the sensed flattenedteeth; means for storing a standard binary code; and means for comparingthe binary codes stored in said storing means.
 3. The apparatus of claim2 wherein said storing means for storing a binary code representative ofthe sensed flattened teeth comprise a serial-input, parallel-outputshift register.
 4. In a chain printer wherein the type carrier has afont set thereon and utilizes a plurality of teeth for engaging drivingmeans, a method for generating a unique binary code identifying the fontset on the type carrier comprising: flattening a plurality of teeth onsaid carrier in a preselected order representative of said unique binarycode; sensing the flattened teeth when said type carrier is driven; andgenerating a binary code representative of the sensed flattened teeth.5. The method of claim 4 further comprising: storing the binary coderepresentative of the sensed flattened teeth; storing a standard binarycode; and comparing the stored binary codes.
 6. In a chain printerwherein the type carrier has a font set thereon and utilizes a pluralityof teeth for engaging driving means, one of said teeth being physicallymodified and sensed by a detection means for generating a synchronizingpulse, apparatus for generating a unique binary code identifying thefont set on the carrier, comprising: an additional plurality ofphysically modified teeth located on said type carrier displaced fromthe physically modified tooth for representing said binary code, saidadditional plurality of physically modified teeth being sensed by saiddetection means; and means responsive to said detection means forgenerating the binary code represented by said representing means. 7.The apparatus of claim 6 further comprising: means for storing thegenerated binary code; means for storing a standard binary code; andmeans for comparing the binary code stored in said storing means.
 8. Theapparatus of claim 7 wherein said physically modified teeth areflattened, and wherein said storing means for storing the binary codegenerated by said detection responsive means comprises a serial-input,parallel-output shift register.
 9. In a chain printer wherein the typecarrier has a font set thereon and utilizes a plurality of teeth forengaging driving means, a method for generating a unique binary codeidentifying the font set on the type carrier, comprising: physicallymodifying a predetermined plurality of said plurality of teeth atpredetermined locations on said type carrier so as to be representativeof said unique binary code; sensing the physical modification of saidpredetermined plurality of said teeth; and generating a binary coderepresentative of the physical modification.
 10. The method of claim 9wherein said physically modIfying comprises flattening saidpredetermined plurality of teeth, and further comprising: storing thegenerated binary code; storing a standard binary code; and comparing thestored binary codes.